JP2004063858A - Method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable elimination of undesired substances, such as flocculated abrasive particles and scrap, without using a filter, when reusing slurry. <P>SOLUTION: Used slurry discharged from polishing equipment, like CMP equipment, is subjected to recycling by concentration adjusting treatment, particle size adjustment treatment and PH adjusting treatment. In the particle size adjusting treatment, treatment is performed by a particle size adjustment treating part 32, which is provided with a flocculated adhesive particle crushing treatment part 40 by ultrasonic irradiation treatment or the like, a temperature separating treatment part 50, wherein flocculated adhesive particles etc. are separated from normal abrasive particles by controlling the slurry at nonuniform temperature, and a flocculated adhesive particle discarding part 60, wherein discarding treatment of separated flocculated adhesive particles etc. is performed. As a result, undesired substances like the abrasive particles is separated from the used slurry without using a filter, and slurry containing adhesive particles whose particle size is normal is collected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor device manufacturing technique, and more particularly to a technique that is effective when applied to a slurry regeneration process in a polishing process.
[0002]
[Prior art]
The technology described below has been studied by the inventor when researching and completing the present invention, and the outline thereof is as follows.
[0003]
At present, the processing cost of a CMP apparatus using a slurry in a semiconductor device is said to be higher than other pre-processing equipment. In particular, the slurry used for CMP polishing accounts for about 30% of the processing cost.
[0004]
Therefore, effective use of the slurry is strongly demanded. In response to such demands, it has been practiced to reduce the amount of waste slurry and reuse the slurry. In the slurry recycling technique, a major technical problem is how to reliably remove foreign matter and agglomerated abrasive grains in the regenerated slurry.
[0005]
If polishing dust generated by the CMP polishing or agglomerated abrasive grains in the used slurry remain without being removed from the regenerated slurry, scratches on the polished surface due to the use of the regenerated slurry occur.
[0006]
In order to remove such agglomerated abrasive grains and polishing debris, a method of removing used slurry (waste liquid) through a filter is generally adopted. However, in the method using a filter, clogging of the filter necessarily occurs, and periodic filter replacement is required.
[0007]
In filter filtration of used slurry from a CMP apparatus, filter clogging occurs in a short time, so filter replacement in the slurry recycling technique must be performed frequently. For this reason, the cost burden of filter maintenance on the operation efficiency and operation cost of the slurry reuse system, such as downtime of the slurry recycling device and increase in filter replacement cost, becomes a major problem. Some have been done.
[0008]
For example, Japanese Patent Application Laid-Open No. H11-347940 discloses that a used polishing slurry is selectively supplied to a plurality of filters, and one filter is processed while the other filter is stopped to replace the filter and to remove the clogging. There is disclosed a polishing system for performing filter maintenance.
[0009]
In such a polishing system, unlike before, the filter maintenance work can be performed without stopping the operation of the polishing apparatus every time maintenance is performed, that is, while operating the polishing apparatus. Time can be eliminated.
[0010]
Japanese Patent Application Laid-Open No. 11-277434 discloses a configuration in which an agglomerated slurry is dispersed by ultrasonic energy while flowing a slurry used in a CMP apparatus, and the slurry is reused in a state close to a dispersed state before use. ing.
[0011]
Japanese Patent Application Laid-Open No. H11-10540 discloses a state in which a slurry used in a CMP apparatus is coarsely filtered by removing a contaminant of a polishing pad, polishing debris and the like by a filtering means for removing foreign substances having a particle diameter of 10 μm or more. Then, pH adjustment and slurry concentration adjustment are performed, and furthermore, agglomerated abrasive grains are removed by a filtering means for removing foreign substances having a particle diameter of less than 10 microns, and the resultant is subjected to precision filtration. The slurry after the precision filtration is supplied from the slurry supply apparatus to the CMP apparatus. A configuration of slurry recycling is disclosed.
[0012]
Japanese Patent Application Laid-Open No. 2002-11664 discloses that waste slurry scattered in a polishing section of a CMP machine is collected, polishing dust and the like are removed by a filtration means, and impurities such as salts and organic substances are further removed by a membrane separation means and the like. There is disclosed a configuration in which concentration is performed after dilution washing and then concentration adjustment is performed to recover the slurry, and the recovered slurry is reused.
[0013]
Japanese Patent Application Laid-Open No. 2000-308967 discloses a configuration in which the recovered slurry is re-dispersed to reuse the slurry. That is, from a high-concentration waste liquid that is a slurry waste liquid containing high-concentration impurities generated by ordinary polishing or the like, coarse impurities other than abrasive particles, which have a bad influence on polishing characteristics, are first removed by a filter, and further filtered by a fine filtration membrane. Removes minute abrasive particles and minute impurities that have deteriorated during polishing.
[0014]
Thereafter, in a state where the temperature control is performed in the heat exchange tank, the dispersion medium at a temperature at which the aggregation of the abrasive particles does not occur, and a dispersion medium adjuster for adjusting the PH of the dispersion medium are adjusted to adjust the concentration of the dispersion medium, The coarse particles in the slurry whose concentration has been adjusted with a dispersant, electromagnetic waves, or ultrasonic waves are redispersed into primary particles or secondary particles to reuse the slurry.
[0015]
Japanese Patent Application Laid-Open No. 2000-263441 discloses a configuration in which water or an unused abrasive slurry is added to a recovered slurry to adjust the concentration to a predetermined concentration and reuse the collected slurry based on the concentration measurement result of the recovered slurry. .
[0016]
[Problems to be solved by the invention]
However, the present inventor has found that there are the following problems in the above-mentioned slurry regeneration treatment technology.
[0017]
That is, by using each of the above proposed techniques, it is possible to effectively eliminate the coagulated abrasive grains in the regenerated slurry and to remove foreign substances such as polishing dust, but it is not yet complete. The presence of agglomerated slurries and polishing debris leads to the generation of scratches, and the reliability of the technology must be improved before such concerns can be sufficiently eliminated. The current situation is still insufficient to ensure the effectiveness of the slurry recycling technology.
[0018]
On the other hand, in a configuration in which a filter is used for removing agglomerated slurry and polishing debris, filter maintenance based on clogging is required. For this reason, it is not possible to avoid problems such as downtime associated with such filter maintenance.
[0019]
On the other hand, a method of providing a plurality of filters and performing the filter work in parallel with the filter maintenance has been proposed as described above. However, even if the problem of downtime can be solved, clogging processing, filter It is not always possible to completely eliminate filter maintenance work for replacement or the like.
[0020]
Filter maintenance work, which is troublesome and time-consuming, will remain. From such a viewpoint, it is preferable to develop a technique for removing coagulated abrasive grains and cutting chips without using a filter.
[0021]
SUMMARY OF THE INVENTION An object of the present invention is to make it possible to eliminate agglomerated slurry and remove cutting chips without using a filter when reusing the slurry.
[0022]
The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0023]
[Means for Solving the Problems]
The following is a brief description of an outline of typical inventions disclosed in the present application.
[0024]
That is, in the present invention, the agglomerated abrasive grains are crushed by ultrasonic irradiation or the like, and the separation between the agglomerated abrasive grains and the normal abrasive grains is performed by non-homogeneous temperature control and sedimentation processing. The slurry containing the appropriate abrasive grains is collected.
[0025]
In such a configuration, the aggregated abrasive grains in the used slurry are regenerated into normal abrasive grains by crushing. For example, by applying abrasive crushing means such as ultrasonic irradiation to used slurry discharged from a polishing apparatus such as a CMP (Chemical Mechanical Polishing) apparatus, the aggregated abrasive grains in the used slurry are crushed, Thus, usable normal abrasive grains can be obtained.
[0026]
On the other hand, the agglomerated abrasive grains remaining in the slurry even after the crushing treatment are performed by controlling the temperature of the upper part of the slurry flow path to a high temperature and the lower part of the flow path to a low temperature while flowing the slurry. By adjusting the temperature of the upper and lower portions of the slurry flowing in the passage non-homogeneously at different temperatures, the agglomerated abrasive grains are concentrated below the flow path, and the separation of the agglomerated abrasive grains and the non-agglomerated abrasive grains in the slurry is performed. Can be promoted.
[0027]
Therefore, the slurry flowing above the flow path does not contain agglomerated abrasive grains, that is, a slurry for recovery including normal abrasive grains that are reusable non-agglomerated abrasive grains, and the slurry flowing below the flow path is agglomerated abrasive grains. It becomes a slurry for disposal containing a high concentration.
[0028]
Slurry for disposal containing a high concentration of agglomerated abrasive grains can be treated separately from the slurry for recovery, for example, by adding an appropriate aggregating agent or the like and aggregating to promote precipitation and discard. .
[0029]
The supernatant liquid obtained by separating the agglomerated abrasive grains from the slurry for disposal is not used as it is as a reused slurry, but is returned to the ultrasonic treatment side again to ensure the removal of the agglomerated abrasive grains for reuse. Plan.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for describing the embodiments, members having the same functions are denoted by the same reference numerals, and repeated description thereof will be omitted.
[0031]
In the present embodiment, first, a slurry recycling system provided in a CMP apparatus used in the method for manufacturing a semiconductor device according to the present invention will be described.
[0032]
FIG. 1 is an explanatory view showing a slurry recycling system of a CMP apparatus used in a polishing step in a method of manufacturing a semiconductor device according to the present invention. FIG. 2 is an explanatory diagram showing a main part of the CMP apparatus.
[0033]
FIG. 3A is a cross-sectional view schematically illustrating a particle size processing unit of the slurry recycling apparatus illustrated in FIG. 1, and FIG. 3B is an explanatory view illustrating a crushing action of aggregated abrasive grains by ultrasonic irradiation. It is. FIG. 4 is an explanatory plan view of a main part schematically showing a particle size processing section having the configuration shown in FIG.
[0034]
As shown in FIG. 1, the slurry recycling system 10 includes a polishing device 20 such as a CMP device 20a used in a polishing process for flattening, and a slurry recycling device 30. Is supplied to the CMP apparatus 20a.
[0035]
In the CMP apparatus 20a (20), as shown in FIG. 2, a polishing pad 23 is provided on a surface plate 22 rotated by a motor 21. A polishing surface of a wafer W provided via a carrier pad 26 is arranged on a wafer carrier 25 rotated by a motor 24 with respect to the surface of the polishing pad 23.
[0036]
In addition, a nozzle 27 connected to a slurry supply device (not shown) by a pipe is provided toward the surface of the polishing pad 23, and the slurry S1 as an abrasive is supplied from the nozzle 27.
[0037]
Using the slurry S1 supplied to the surface of the polishing pad 23 in this manner, the polishing surface of the wafer W is planarized while rotating the polishing surfaces of the wafer W facing the polishing surface of the polishing pad 23 with each other. .
[0038]
On the other hand, as shown in FIG. 1, the slurry recycle device 30 includes a concentration adjustment processing unit 31, a particle size adjustment processing unit 32, and a PH adjustment processing unit 33.
[0039]
The concentration adjustment processing section 31 is provided with an adjustment tank (not shown) into which the used slurry S2 from the CMP apparatus 20a flows, and in the adjustment tank, the mixed pure water is separated to concentrate the slurry S2, and the next particle is removed. It is sent to the diameter adjustment processing unit 32.
[0040]
The particle size adjustment processing unit 32 is a step that greatly affects the slurry quality in the slurry recycling processing technology, and is formed in a flow path 32a through which the concentrated used slurry S2 flows, as shown in FIG. . In the flow path 32a, an agglomerated abrasive crushing section 40, a temperature separation processing section 50, and an agglomerated abrasive grain disposal section 60 are sequentially configured toward the downstream side.
[0041]
In FIG. 3A, the ranges of the coagulated abrasive crushing unit 40 and the temperature separation unit 50 are indicated by double arrows, but in practice, the boundary between the two processing units is strictly divided. This is not possible, and the processing is performed in a state where the agglomerated abrasive grain crushing processing and the temperature separation processing are slightly overlapped at the boundary portion.
[0042]
In the agglomerated abrasive crushing unit 40, a vibrator 42 connected to an ultrasonic oscillator 41 constituted by an oscillator or the like is provided on the wall surface of the flow path 32a. By vibrating the vibrator 42, the concentrated used slurry S2 flowing in the flow path 32a is irradiated with ultrasonic waves.
[0043]
Ultrasonic irradiation generates a large number of cavitation bubbles (bubbles) in the slurry, and the energy generated when the large number of generated cavitation bubbles pops out, that is, crushes the aggregated state of the aggregated abrasive grains present in the slurry by the impact microwave. Then, it is intended to diffuse the generated normal abrasive grains. Such a state is schematically shown in FIG.
[0044]
In the figure, X represents aggregated abrasive grains such as aggregated silica contained in the slurry S2, and Y represents normal abrasive grains that have not aggregated such as normal silica particles. In addition, machining waste such as pad waste, falling diamond, and retainer waste is indicated by Z.
[0045]
In the temperature separation processing section 50, the flow path bottom surface 51 side is formed as an inclined surface that is inclined obliquely downward toward the downstream side, and reaches the branch portion. By providing such a gradient, the flow can be made easier. In the branch portion, a recovery channel 52 through which a used slurry S2a (S2) containing normal abrasive grains Y as non-agglomerated abrasive grains flows, and a used slurry S2b containing a high concentration of aggregated abrasive grains X below. A disposal channel 53 through which (S2) flows is provided.
[0046]
The temperature separation processing section 50 is provided with a temperature control function capable of controlling the temperature non-uniformly in the height direction. On the upper side of the flow path, for example, a heater 55 is provided on the side of the flow path ceiling 54, so that the temperature of the used slurry S2 can be controlled to a high temperature such as 100 to 120 ° C. by controlling the temperature of the heater. I have.
[0047]
On the other hand, a chiller unit 56 that cools the used slurry S2 to a degree that does not freeze the used slurry S2 is provided on the channel bottom surface 51 side, so that the temperature of the slurry S2 can be controlled to a low temperature such as 0 to 10 ° C. by chiller temperature control. It has become.
[0048]
In addition, the temperature separation processing unit 50 having the above configuration is provided continuously with the coagulated abrasive crushing unit 40 without providing a special partition or the like in the integrally formed flow path 32a. As compared with the case where the method is not adopted, the influence of the ultrasonic wave applied in the coagulation abrasive crushing unit 40 also affects the temperature separation processing unit 50 to some extent, thereby promoting the prevention of the adhesion of the coagulation abrasive X to the flow path wall surface. Can be achieved.
[0049]
The recovery flow path 52 is provided with a flow rate adjusting valve 71a as a recovered slurry flow rate adjusting means 71 and a particle size measuring instrument 72a as a particle size measuring means 72. The downstream side of the particle size measuring instrument 72a is provided with, for example, a PH adjustment shown in FIG. This leads to the next recycle processing of the processing unit 33 and the like.
[0050]
The flow path for disposal 53 is provided with a flow rate adjusting valve 73 a as a coagulated abrasive particle collecting flow rate adjusting means 73. The downstream side of the flow control valve 73a is connected to an agglomerate abrasive grain sedimentation tank 81 as shown in FIG. Above the agglomerated abrasive sedimentation tank 81, a supernatant liquid in which the agglomerated abrasives X are precipitated from the used slurry S2b (S2) that has flowed in (which may be regarded as a slurry having a substantially lower abrasive concentration). A (superior) liquid outlet 82 is provided for returning S2c to the coagulated abrasive crushing section 40.
[0051]
Below the agglomerated abrasive sedimentation tank 81, an agglomerated abrasive outlet 83 is provided, so that the supernatant liquid S2c and the slurry S2d containing the agglomerated abrasive grains X separated by settling at a high concentration are discarded. I have.
[0052]
The coagulation abrasive sedimentation tank 81 is provided with a liquid level sensor 84 at a predetermined depth, and an automatic valve 85 that is automatically opened and closed by a signal from the liquid level sensor 84 is provided upstream of the coagulation abrasive discharge port 83. I have. With the agglomerated abrasive outlet 83 closed, sedimentation processing of the agglomerated abrasive X and processing waste Z in the inflowing slurry S2b is performed, while the supernatant S2c is subjected to the agglomerated abrasive crushing as described above. It is refluxed to the used slurry reprocessing unit such as the unit 40.
[0053]
The agglomerated abrasive grains X and the processing waste Z are separated from the supernatant liquid S2c and settle and accumulate in the agglomerated abrasive grain sedimentation tank 81. The liquid level sensor 84 detects that the slurry S2d has reached a predetermined amount, the automatic valve 85 is opened, and the stored agglomerated abrasive grains X and the like are discarded as waste slurry S2d.
[0054]
After the disposal, the automatic valve 85 is automatically closed to separate the agglomerated abrasive grains of the slurry S2b flowing in from the supernatant S2c as described above. The waste Z is disposed of.
[0055]
Although not shown, the PH adjustment processing section 33 is provided with a pH adjustment tank, and an ultrapure water addition section for injecting ultrapure water into the PH adjustment tank, and a slurry containing normal abrasive grains in a high concentration are added. And a chemical liquid addition section for adding a chemical liquid for adjusting the liquid properties and the like as needed.
[0056]
The required amount of ultrapure water, slurry, chemical solution, etc. is added to the recovered slurry S2a that has flowed into the PH adjustment tank so that the abrasive particle concentration and the liquid property have a predetermined PH, thereby preparing a recycled slurry. In this way, the slurry S2a that has been processed by the PH adjustment processing unit 33 is supplied to the CMP apparatus 20a as a recycled slurry.
[0057]
Although not shown, the CMP device 20a is provided with a new slurry supply device, and the slurry is supplied to the CMP device 20a in a state where the new slurry and the recycled slurry are merged.
[0058]
In the above description, the case where the flow path 32a is formed in a rectangular cross section as shown in FIGS. 3 and 4 is shown, but the cross sectional shape of the flow path 32a is not limited to such a rectangular shape, and may be any shape in which the slurry flows smoothly. If it is, there is no particular limitation on the shape. In FIGS. 3 and 4, the vibrator 42 for ultrasonic oscillation is formed on both side walls so as to sandwich the slurry flowing through the flow path 32a in a substantially rectangular cross section. For example, it is preferable that the width of the flow path is smaller than that in the height direction so that the shock microwave or the like is uniformly irradiated and does not attenuate.
[0059]
Regarding the height of the flow path, it is preferable that the height of the flow path is as high as possible in order to enhance the separability between the agglomerated abrasive grains X, the processing dust Z, and the normal abrasive grains Y. That is, in a flow path having a substantially square cross section, it is preferable that the side face of the flow path on which the vibrator 42 is provided is made higher to form a square with a vertically long cross section.
[0060]
On the other hand, in terms of the flow path length, it is preferable that the length is slightly longer in consideration of the natural separation of the agglomerated abrasive grains X, the processing waste Z, and the normal abrasive grains Y by gravity.
[0061]
In the case shown in FIGS. 3 and 4, a configuration is shown in which the agglomerated abrasive crushing unit 40, the temperature separation processing unit 50, and the agglomerated abrasive particle disposal unit 60 are sequentially formed downstream. In order to promote the separation between the agglomerated abrasive grains X, the processing waste Z, and the normal abrasive grains Y, it is preferable to set the flow path length to be long as described above.
[0062]
That is, it is desired that both the coagulated abrasive crushing section 40 and the temperature separation section 50 have a configuration that can secure the flow path length as much as possible. However, on the other hand, setting such a long flow path length goes against the flow of technical demands for downsizing and space saving of the semiconductor manufacturing apparatus.
[0063]
Therefore, as shown in FIG. 5, the inventor of the present invention applied both the agglomerated abrasive crushing unit 40 and the temperature separation unit 50 so that both the crushing unit and the temperature separation unit were used. It has been found that the flow can be performed with the flow path length that is added with That is, although the flow path length is the same as that shown in FIGS. 3 and 4, the processing flow path length for the coagulated abrasive crushing process and the temperature separation process can be substantially extended.
[0064]
In the case shown in FIG. 5, the flow path 32a is formed such that the flow path bottom surface 51 is inclined obliquely downward toward the branch portion. A heater 55 is provided on the flow channel ceiling 54 side toward the branch portion side, and the upper side of the slurry S2 flowing in the flow channel 32a can be controlled to a high temperature, for example, at 100 to 120 ° C. by the heater temperature control. It has become.
[0065]
A chiller unit 56 is provided on the side of the flow channel bottom surface 51 toward the branch portion, so that the temperature of the lower side of the flow channel of the slurry S2 flowing in the flow channel 32a can be controlled to, for example, 0 to 10 ° C. by chiller temperature control. It has become. The configuration after the branching unit is the same as that shown in FIG.
[0066]
In such a configuration, as shown by the double-headed arrow in FIG. 5, the coagulated abrasive crushing unit 40 and the temperature separation unit 50 are set within the same range. Therefore, unlike the case where the agglomerated abrasive crushing unit 40 and the temperature separation processing unit 50 are sequentially configured, the flow path length of the agglomerated abrasive crushing unit 40 shown in FIG. With the total flow path length including the flow path length, the crushing process of the aggregated abrasive grains can be performed. Further, the temperature separation between the crushed agglomerated abrasive grains and the normal abrasive grains is also performed within the total flow path length.
[0067]
That is, the crushing process and the temperature separation process are performed in parallel within the total flow path length. Therefore, as compared with the case where the crushing process and the temperature separation process are sequentially performed as in the case of the configuration shown in FIG. 3, the time required for the crushing process can be increased, and the crushing process is accelerated accordingly. Further, the time left to the temperature separation treatment can be increased, and the separation is accelerated accordingly.
[0068]
Such promotion of the crushing process and the promotion of the separation process are combined to promote the regeneration of the normal abrasive grains from the used slurry and the separability from the agglomerated abrasive grains. The slurry S2a containing normal abrasive grains Y in which X is not mixed in high concentration can be efficiently collected.
[0069]
In addition, when the temperature separation processing unit 50 is separately provided, there is a possibility that the agglomerated abrasive grains X adhere to the inner wall surface of the flow channel. However, by using the agglomerated abrasive grain crushing processing unit 40 performing the ultrasonic treatment together, In addition, the wall surface of the agglomerated abrasive grains X due to ultrasonic waves is prevented. In addition, the crushing process and the gravity sedimentation process are performed in parallel.
[0070]
Next, a technique for reusing slurry using the slurry recycling system having the above-described configuration will be described with reference to FIG. In the following description, a case in which silica is used as the slurry as the slurry will be exemplified.
[0071]
As shown in FIG. 1, the used slurry discharged from the CMP device flows into the concentration adjustment processing unit 31. In the concentration adjustment processing section 31, pure water in the slurry is removed and concentrated. For example, the silica concentration of the abrasive grains is adjusted to a predetermined concentration.
[0072]
The slurry S2 thus concentrated in the concentration adjustment processing unit 31 flows into the particle size adjustment processing unit 32 as a waste liquid slurry as shown in FIG. In the particle size adjustment processing section 32, the slurry S2 that has flowed flows in the flow path 32a.
[0073]
In the present description, as an example of the configuration inside the flow path 32a, as shown in FIG. 3, a configuration in which an agglomerated abrasive crushing unit 40 and a temperature separation processing unit 50 are sequentially provided is exemplified. Will be explained.
[0074]
The inflow amount of the slurry S2 is controlled by opening and closing the flow control valves 71a and 73a. Ultrasonic waves are applied to the slurry S2 flowing into the flow path 32a through the vibrator 42 provided on the side wall of the flow path 32a while flowing.
[0075]
The ultrasonic irradiation generates countless cavitation bubbles in the slurry S2. When the cavitation bubbles burst, shock microwaves are generated, and the energy thereof causes the aggregated silica (agglomerated abrasive grains) to break into individual silica particles. As a result, non-agglomerated normal silica particles are regenerated. In FIG. 6, such a situation is shown in step S110 as the aggregated silica crushing.
[0076]
That is, in the slurry S2, the crushing of the aggregated silica and the accompanying regeneration of the normal silica are performed while flowing through the aggregated abrasive crushing unit 40 of the flow path 32a. Flowing inside.
[0077]
In the temperature separation processing section 50, the upper side of the slurry S2 flowing in the flow path is heated to a high temperature of, for example, 100 to 120 ° C. by the heater 55 provided on the flow path ceiling 54. On the other hand, the lower side of the slurry S2 is cooled to, for example, a low temperature of 0 to 10 ° C. by the chiller unit 56 provided on the flow path bottom surface 51.
[0078]
As described above, in the slurry S2 flowing in the temperature separation processing section 50 of the flow path 32a, non-homogeneous temperature control in which a temperature difference is provided between the upper part of the flow path and the lower part of the flow path is performed. In the non-homogeneously heated slurry S2, utilizing the fact that the total of recoil speeds at the time of collision between liquid particles and solid particles such as aggregated silica, processing waste, and normal silica goes to the low-temperature region, the aggregated silica, Separation of processing waste from normal silica is performed in conjunction with separation based on gravity precipitation.
[0079]
In other words, the remaining aggregated silica and the processing dust that have not been sufficiently crushed even by the crushing process of the aggregated abrasive particles by the ultrasonic irradiation are collected below the flow path 32a by the above-mentioned non-homogeneous heating of the slurry S2 as the waste liquid slurry. It is separated from the normal silica which flows in a dispersed manner. Above the flow path, a normal slurry S2a containing normal silica as abrasive grains is thus generated. This situation is shown in FIG. 6 as the separation of the normal slurry and the solid particles in step S120.
[0080]
The slurry S2b containing the aggregated silica, processing waste, and partly normal silica collected below the flow path flows into the waste flow path 53 from the branch portion, and flows into the aggregated abrasive grain sedimentation tank 81. In FIG. 6, such a situation is shown in step S130 as solid particles (residual aggregated silica + processed chips) + partially normal silica slurry.
[0081]
The slurry S2b containing such a high concentration of the aggregated silica is set in the aggregated-abrasive-grain sedimentation tank 81 by adjusting the flow rate control valve 73a, so that the aggregated silica and the processing dust are precipitated in the agglomerated-abrasive-grain sedimentation tank 81. And separated from the supernatant. In FIG. 6, such a situation is shown in steps S140 and S150, respectively.
[0082]
The supernatant liquid S2c shown in Step S140 is returned to the coagulated abrasive crushing section 40 from the supernatant liquid outlet 82. The supernatant liquid S2c is a normal silica slurry in which a part of normal silica mixed with the aggregated silica slurry flowing into the aggregated abrasive grain precipitation tank 81 is dispersed.
[0083]
The supernatant S2c is sent to the coagulation abrasive crushing section 40 as shown in FIG. Since the supernatant liquid S2c is a slurry obtained by separating the aggregated silica by precipitation from the slurry S2b containing the aggregated silica at a high concentration, the removal of the aggregated silica may be insufficient. Therefore, the supernatant S2c is sent to the agglomerated abrasive crushing unit 40 along the route R indicated by the arrow in FIG. 6, and the agglomerated silica that may be present in the supernatant S2c is crushed.
[0084]
On the other hand, the sediment such as the remaining agglomerated silica and processing chips precipitated in the agglomerated abrasive grain sedimentation tank 81 shown in step S150 is discharged in a state of slurry S2d from the agglomerated abrasive grain discharge port 83 as shown in step S160. Will be discarded.
[0085]
At the time of such disposal, the automatic valve 85 is opened by the liquid level sensor 84 provided in the agglomerated abrasive grain sedimentation tank 81 while the slurry S2d of the agglomerated silica of the predetermined concentration has accumulated to the predetermined depth. It is only necessary to discharge automatically.
[0086]
Further, the slurry S2a that has flowed into the recovery flow channel 52 provided above the flow channel at the branch portion has flowed in a state where coagulated silica and processing waste have already been removed in the temperature separation processing portion 50 and non-coagulated normal silica is contained. It will be. The flow rate of the slurry S2a is adjusted by the flow rate adjustment valve 71a provided in the recovery flow path 52 so that the normal slurry flows most. This situation is shown in FIG. 6 as normal silica slurry in step S170.
[0087]
As can be seen from the above description, the normal silica slurry shown in step S170 is subjected to ultrasonic treatment for the used slurry S2 to crush the aggregated abrasive grains X, and to promote separation of the aggregated abrasive grains X by controlling the temperature. It is not necessary to use a chemical solution such as a dispersant and a precipitation accelerator.
[0088]
As described above, in the above-described configuration, although the concentration of the slurry component changes, the slurry component does not change, so that it is not necessary to perform a troublesome process such as removal of a chemical solution. A recycled slurry can be formed by relatively simple adjustment of liquid properties such as concentration, pH and the like.
[0089]
Further, since a chemical solution is not used, there is no risk of contamination of the surrounding environment due to the disposal of the chemical solution even when the agglomerated abrasive particles are discarded.
[0090]
The normal silica slurry, which has been flow-regulated by the flow control valve 71a and entered the recovery flow channel 52, is subjected to a particle size check of the silica particles in the normal silica slurry by the particle size measuring device 72a on the way, and contains no aggregated silica. To be monitored.
[0091]
Based on the result of the particle size measurement, when a large particle size or a tendency to increase the particle size is detected, the flow rate control valves 71a and 73a are closed and adjusted based on a signal from the particle size measuring device 72a to adjust the waste liquid slurry. For example, the staying time in the agglomerated abrasive crushing unit 40 and the temperature separation processing unit 50 is increased to promote the agglomerated abrasive crushing process and promote the separation of solid particles such as agglomerated silica from normal silica.
[0092]
At the same time, the result of the particle size measurement is fed back to the agglomerated abrasive crushing section 40, and the oscillating ultrasonic waves are strengthened to enhance the crushing of the agglomerated abrasive.
[0093]
If it is confirmed by the particle size measurement that the coagulated abrasive grains are present in the recovered slurry, the flow rate control valve 71a is closed in real time, and the collected slurry is sent to the PH adjustment processing unit 33 which is the next recycling process. Interrupt. At the same time, as described above, the ultrasonic intensity, the frequency, the heater temperature, the chiller temperature, and the flow control valve are readjusted so that the aggregated abrasive particles are not included in the recovered slurry.
[0094]
By providing the particle size measuring device in-line in this way, it is possible to control the particle size and the number of abrasive grains in the recovered slurry, and to control the quality of the recovered slurry to supply a highly reliable recycled slurry. Can be.
[0095]
The normal silica slurry, which has been checked for coagulation of aggregated silica in this manner and is in a sufficiently usable state, is sent to the PH adjustment processing unit 33 shown in FIG. 1, where the silica concentration in the slurry and the pH of the slurry are adjusted. Adjustments will be made. This situation is shown in FIG. 6 as the next recycling process in step S180. As shown in FIG. 1, the slurry after the recycle processing is supplied to the CMP apparatus 20a as a recycle slurry and used for polishing.
[0096]
As is clear from the above description, the configuration described above does not merely separate the aggregated abrasive grains from the used slurry from the normal abrasive grains, but crushes the aggregated abrasive grains to temporarily regenerate the normal abrasive grains. Then, the regenerated normal abrasive grains are separated from the remaining aggregated abrasive grains. Until then, normal abrasive grains were reclaimed from agglomerated abrasive grains, which had been discarded because there was no treatment method. Can be higher.
[0097]
For this reason, the slurry cost is also reduced to half or less of the case where such a configuration is not adopted, and the slurry cost is positively reduced.
[0098]
As is clear from the above description, in the configuration of the present invention, without using a filter, the aggregated abrasive grains and processing wastes from the used slurry can be separated from the normal abrasive grains. No filter maintenance is required.
[0099]
Therefore, in addition to the reduction in the slurry cost, as a result, the overall running cost of the polishing process such as the CMP process is reduced.
[0100]
As described above, the waste slurry recycling system has been described by taking the configuration shown in FIG. 3 as an example, but the flow of the recycling system is basically the same as the configuration shown in FIG. The difference is that the temperature separation process is performed in parallel.
[0101]
From the viewpoint of a method for manufacturing a semiconductor device, the slurry recycling system described above can be applied in a polishing process using a slurry such as a CMP device. For example, it can be used in a planarization process by CMP polishing such as a planarization process of an interlayer insulating film, a trench isolation formation process, and a buried metal wiring process in a series of semiconductor device manufacturing processes.
[0102]
For example, a case where the present invention is applied to flattening of an interlayer insulating film of a logic ULSI will be described. A base transistor is formed on a wafer substrate, and SiO (chemical vapor deposition) is formed on the base transistor. ₂ Is deposited to form an interlayer insulating film. The unevenness of the interlayer insulating film is ₂ Is flattened by CMP polishing using a slurry containing as abrasive grains. The slurry used in the planarization is sent as used slurry, for example, to the slurry recycling system shown in FIG.
[0103]
In the slurry recycling system, the slurry is recycled as a recycled slurry through a concentration adjustment processing unit 31, a particle size adjustment processing unit 32, and a PH adjustment processing unit 33, supplied to a CMP apparatus, and reused. The processing contents of the concentration adjustment processing unit 31, the particle size adjustment processing unit 32, and the PH adjustment processing unit 33 may be performed as described above, and the description will not be repeated.
[0104]
As described above, an Al film is deposited by a sputtering method or the like on the interlayer insulating film planarized in the CMP polishing step of reusing the slurry using a recycling system. Further, patterning by photolithography and patterning by reactive ion etching are performed. SiO2 is formed on the wiring thus formed by CVD. ₂ Is deposited, and an interlayer insulating film is formed again. The interlayer insulating film is planarized in the same CMP process as above while recycling the slurry.
[0105]
By repeating such a process a required number of times, a semiconductor device having a logic ULSI structure having an interlayer insulating film that has been planarized by CMP and has a slurry recycling process can be manufactured.
[0106]
In addition, the above-described configuration according to the present invention is not limited to the flattening step, and can be applied to, for example, recycling of a slurry for crystal polishing such as silicon crystal of a wafer. Furthermore, the present invention can be effectively applied to a technique for separating a solid dispersed in a liquid from the aggregated solid.
[0107]
As described above, the invention made by the inventor has been specifically described based on the embodiment of the invention. However, the invention is not limited to the embodiment of the invention, and various modifications may be made without departing from the gist of the invention. It goes without saying that it is possible.
[0108]
For example, in the above-described embodiment, the case where the supernatant liquid separated from the solid particles subjected to the precipitation treatment in the agglomerated abrasive particle disposal processing unit 60 is returned to the agglomerated abrasive particle crushing processing unit 40 has been described. A particle size measuring device is provided in front of the supernatant discharge port 82 of the aggregated abrasive sedimentation 81, and is sent to the aggregated abrasive crushing unit 40 via the route R only when mixed silica is observed. A configuration is also conceivable. In the case where no coagulated silica is present, the coagulated silica can be combined with the normal silica particle slurry, which is more efficient than the case where the coagulated silica is uniformly returned to the coagulated abrasive crushing section.
[0109]
In the above-described embodiment, the configuration in which the filter is not used in the particle size adjustment processing unit is described. However, in the concentration adjustment processing unit before the particle size adjustment processing unit, for example, a limit filtration membrane (UF membrane) is used. No problem. If such a ultrafiltration membrane is used, pure water can be separated and concentrated from the waste liquid slurry, and both the slurry and the pure water can be recycled.
[0110]
Also, a plurality of recycling systems may be provided according to the amount of waste liquid slurry to be processed. Alternatively, a plurality of particle size processing units may be provided for the concentration adjustment processing unit.
[0111]
The configuration of the present invention eliminates the need for filter maintenance related to filter clogging by adopting a configuration that does not use a filter, but does not necessarily exclude the use of the filter together. For example, by using a membrane filter in combination with the system of the present invention, maintenance of the membrane filter occurs, but high-quality slurry can be recycled.
[0112]
【The invention's effect】
The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.
[0113]
Unnecessary substances such as agglomerated abrasive grains and processing dust are removed from the used slurry discharged from the polishing step without using a filter, and a slurry of normal abrasive grains can be collected and recycled as a recycled slurry.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an example of a process in a slurry recycling system of a CMP apparatus used in a polishing step of a semiconductor device manufacturing method of the present invention.
FIG. 2 is an explanatory diagram showing a main part of a CMP apparatus.
3A is a cross-sectional view schematically illustrating a main part of a particle size processing unit of the slurry recycling apparatus illustrated in FIG. 1, and FIG. 3B is a view illustrating a crushing action of aggregated abrasive grains by ultrasonic processing. FIG.
FIG. 4 is an explanatory plan view of a main part schematically showing a particle size processing unit having the configuration shown in FIG. 3;
FIG. 5 is an explanatory diagram showing a configuration in which a particle size adjusting processing unit can apply agglomerated abrasive grain crushing processing and temperature separation processing in an overlapping manner.
FIG. 6 is a flowchart showing a processing procedure of a particle size processing unit.
[Explanation of symbols]
10. Slurry reuse system
20 polishing equipment
20a CMP equipment
21 Motor
22 surface plate
23 Polishing pad
24 motor
25 Wafer carrier
26 Carrier pad
27 nozzle
30 Slurry recycling equipment
31 Density adjustment processing unit
32 Particle size adjustment processing unit
32a channel
33 PH adjustment processing unit
40 Agglomeration abrasive crushing unit
41 Ultrasonic oscillator
42 vibrator
50 Temperature separation processing section
51 Channel bottom
52 Recovery channel
53 Waste channel
54 Channel ceiling
55 heater
56 chiller unit
60 Agglomerate abrasive waste disposal unit
71 Recovered slurry flow rate adjusting means
71a Flow control valve
72 Particle size measuring means
72a particle size analyzer
73 Aggregated abrasive collection flow rate adjustment means
73a Flow control valve
81 Agglomerated abrasive sedimentation tank
82 Supernatant outlet
83 Agglomerated abrasive outlet
84 Liquid level sensor
85 Automatic valve
R route
S1 slurry
S2 slurry
S2a slurry
S2b slurry
S2c supernatant
S2d slurry

Claims (5)

A method for manufacturing a semiconductor device having a step of reusing a slurry used in a polishing step,
In the recycling step, the slurry used in the polishing step,
A crushing process for performing coagulation and crushing of the coagulated abrasive grains in the slurry,
Separation of the agglomerated abrasive grains and the non-agglomerated abrasive grains in the slurry, applying a temperature separation process performed by controlling the temperature of the slurry,
A method for manufacturing a semiconductor device, comprising recovering a slurry containing the non-agglomerated abrasive grains. A method for manufacturing a semiconductor device having a step of reusing a slurry used in a polishing step,
In the recycling step, the slurry used in the polishing step,
A crushing process for performing coagulation and crushing of the coagulated abrasive grains in the slurry,
Separation of the agglomerated abrasive grains and the non-agglomerated abrasive grains in the slurry, applying a temperature separation treatment performed by controlling the temperature of the slurry, recovering the slurry containing the non-agglomerated abrasive grains,
A method of manufacturing a semiconductor device, comprising: applying a precipitation treatment to a slurry containing the aggregated abrasive particles separated by the temperature separation treatment, and discarding the precipitated aggregated abrasive particles. A method for manufacturing a semiconductor device having a step of reusing a slurry used in a polishing step,
In the recycling step, the slurry used in the polishing step,
A crushing process of coagulating and crushing the coagulated abrasive grains in the slurry by ultrasonic waves,
By performing non-homogeneous temperature control of the slurry so that the lower side of the slurry is lower than the upper side, the agglomerated abrasive grains and the non-agglomerated abrasive grains are separated, and the slurry containing the non-agglomerated abrasive grains is recovered. A method of manufacturing a semiconductor device. A method for manufacturing a semiconductor device having a step of reusing a slurry used in a polishing step,
In the recycling step,
While flowing the concentrated slurry of the slurry used in the polishing step, crush the aggregated abrasive grains contained in the concentrated slurry by irradiating ultrasonic waves in the aggregated abrasive crushing section,
The temperature control on the upper side of the flow path of the concentrated slurry is a non-homogeneous temperature control that controls the temperature higher than the chiller temperature control on the lower side of the flow path, and the remaining aggregated abrasive grains are separated from the non-agglomerated abrasive grains on the lower side of the flow path,
The concentrated slurry containing the non-agglomerated abrasive is flow-adjusted to the slurry collection side by adjusting the flow rate, supplied to the polishing step as a recycled slurry by adjusting the concentration and PH,
The concentrated slurry containing the remaining agglomerated abrasive grains separated on the lower side of the flow path is flowed to the sedimentation treatment side by adjusting the flow rate, and the remaining agglomerated abrasive grains precipitated are discarded, and the separated agglomerated abrasive grains are separated from the remaining agglomerated abrasive grains. A method for manufacturing a semiconductor device, comprising: flowing a clear liquid into the coagulated abrasive crushing section. A method for manufacturing a semiconductor device having a step of reusing a slurry used in a polishing step,
It is provided between flow paths for flowing the slurry used in the polishing step,
Agglomerated abrasive crushing processing unit for performing agglomeration and crushing of the agglomerated abrasive grains in the slurry,
A temperature separation processing unit that is provided above and below the flow path and has a temperature control unit that makes the temperature on the upper side of the flow path higher than the temperature on the lower side of the flow path;
A branch part provided on the downstream side of the temperature separation processing part, a recovered slurry flow rate adjusting means, a slurry collecting part communicating through a particle size measuring means,
A settling tank provided with a supernatant liquid outlet for sending the supernatant to the coagulated abrasive crushing section and an agglomerated abrasive discharge port for discharging the settled coagulated abrasive, the coagulated abrasive collected in the branch section. Using a slurry recycling system having an agglomerated abrasive waste disposal unit having a flow rate adjusting means,
The particle size measuring means measures the particle size of the abrasive grains in the recovered slurry, and when it is determined that there is a danger of inflow of the agglomerated abrasive grains in the recovered slurry, or the danger of inflow, the recovered slurry flow rate adjusting means, A method for manufacturing a semiconductor device, wherein a flow rate is suppressed by a particle recovery flow rate adjusting means, and a residence time of a used slurry in the agglomerated abrasive grain crushing processing section and the temperature separation processing section is lengthened.

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